U.S. patent application number 12/965598 was filed with the patent office on 2011-06-16 for wastewater treatment systems and methods.
This patent application is currently assigned to PURESTREAM TECHNOLOGY, LLC. Invention is credited to Clayton R. Carter, Janos I. Lakatos, Edward Clay Slade.
Application Number | 20110139378 12/965598 |
Document ID | / |
Family ID | 44141609 |
Filed Date | 2011-06-16 |
United States Patent
Application |
20110139378 |
Kind Code |
A1 |
Lakatos; Janos I. ; et
al. |
June 16, 2011 |
WASTEWATER TREATMENT SYSTEMS AND METHODS
Abstract
A fluid evaporation system includes a housing bounding a fluid
reservoir and an air flow path that is disposed over top of the
fluid reservoir. The housing has an inlet opening and a spaced
apart outlet opening that both provide communication between the
outside environment and the air flow path. A blower is positioned
to draw the air into the air flow path and force the air through
the outlet opening. A misting system positioned within the air flow
path increases the water content of the air stream. A demister is
positioned upstream from the outlet opening and downstream from the
misting system.
Inventors: |
Lakatos; Janos I.; (Mendon,
UT) ; Slade; Edward Clay; (North Logan, UT) ;
Carter; Clayton R.; (North Logan, UT) |
Assignee: |
PURESTREAM TECHNOLOGY, LLC
Salt Lake City
UT
|
Family ID: |
44141609 |
Appl. No.: |
12/965598 |
Filed: |
December 10, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61285870 |
Dec 11, 2009 |
|
|
|
Current U.S.
Class: |
159/4.01 ;
159/48.2 |
Current CPC
Class: |
C02F 1/16 20130101; C02F
1/56 20130101; C02F 9/00 20130101; C02F 2209/02 20130101; C02F
1/048 20130101; C02F 2101/322 20130101; B01D 1/14 20130101; B01D
1/16 20130101; C02F 2101/32 20130101; C02F 2209/03 20130101; B01D
1/305 20130101; C02F 2209/005 20130101; C02F 1/12 20130101; C02F
1/66 20130101 |
Class at
Publication: |
159/4.01 ;
159/48.2 |
International
Class: |
B01D 1/16 20060101
B01D001/16; B01D 1/14 20060101 B01D001/14; C02F 1/12 20060101
C02F001/12; C02F 1/16 20060101 C02F001/16 |
Claims
1. A fluid evaporation system, comprising: a housing assembly
providing a fluid reservoir, the housing including an evaporator
housing bounding an air flow path that that communicates with the
fluid reservoir; an inlet opening formed at a first location of the
housing assembly, the inlet opening being configured to introduce
air from outside of the housing into the air flow path; an outlet
opening formed at a second location of the housing assembly and
communicating with the air flow path; a blower for forcing air into
the air flow path and out the outlet opening; a misting system
configured to spray fluid pooled within the fluid reservoir into
the air flow path; and a demister positioned downstream from the
misting system and within the air flow, the demister positioned
upstream from the outlet opening and including at least one water
coalescing pad configured to remove suspended water droplets from
the airflow.
2. The fluid evaporation system as recited in claim 1, wherein the
at least one water coalescing pad has a specific surface area in a
range from about 10 m.sup.2/m.sup.3 to about 500
m.sup.2/m.sup.3.
3. The fluid evaporation system as recited in claim 1, wherein the
at least one water coalescing pad includes a plurality of wall
structures configured to form channels in fluid communication with
the air flow path.
4. The fluid evaporation system as recited in claim 1, wherein the
at least one water coalescing pad includes a wire mesh.
5. The fluid evaporation system as recited in claim 4, wherein the
wire mesh has a specific surface area in a range from about 50
m.sup.2/m.sup.3 to about 250 m.sup.2/m.sup.3.
6. The fluid evaporation system as recited in claim 4, wherein the
wire mesh is configured to remove suspended water droplets less
than 20 microns in diameter.
7. The fluid evaporation system as recited in claim 1, further
comprising a sprayer system positioned downstream from the demister
and configured to spray a fluid on a surface of the demister.
8. The fluid evaporation system as recited in claim 7, wherein the
sprayer system includes a pump in fluid communication with a source
of wastewater from a well source.
9. The fluid evaporation system as recited in claim 1, further
comprising: a temperature sensor and a humidity sensor positioned
inside or outside of the housing; the blower comprising a variable
speed blower; and a CPU electrically coupled with the temperature
sensor, humidity sensor, and the blower, the CPU being configured
to automatically adjust the speed of the blower based on the
reading from the temperature sensor or the humidity sensor.
10. The fluid evaporation system as recited in claim 1, further
comprising wastewater having a pH less than about 7.0 disposed
within the fluid reservoir.
11. The fluid evaporation system as recited in claim 1, wherein the
housing assembly further comprises one or more exit stacks, the
demister being positioned within the exit stack.
12. The fluid evaporation system as recited in claim 1, further
comprising means for blowing heated air into the air flow path.
13. A method for evaporating a fluid, the method comprising:
pooling a fluid within a reservoir within a housing assembly, the
housing assembly including an evaporator housing bounding an air
flow path that communicates with the reservoir, the air flow path
extending from an air inlet opening in the housing assembly to an
air outlet opening in the housing assembly; creating a flowing air
stream wherein air in the environment outside of the housing flows
into the air flow path through the air inlet opening, travels along
the air flow path, and then exits out of the housing through the
air outlet opening; spraying the fluid within the reservoir into
the air flow path within the evaporator housing; and coalescing
suspended water droplets in the air stream on a demister upstream
from the air outlet opening and downstream from the reservoir, the
demister including at least one water coalescing pad configured to
coalesce suspended water droplets in the air stream.
14. The method as recited in claim 13, wherein the step of
coalescing suspended water droplets includes removing at least
about 50% by weight of water droplets in the air flow stream having
a size between about 1 micron and about 20 microns.
15. The method as recited in claim 13, wherein the at least one
water coalescing pad comprises a wire mesh.
16. The method as recited in claim 13, wherein the step of
coalescing suspended water droplets includes removing at least
about 50% by weight of water droplets in the air flow stream having
a size between about 20 micron and about 100 microns.
17. The method of claim 13, further comprising wetting a downstream
surface of the demister at intervals.
18. The method of claim 17, further comprising spraying at least a
portion of the downstream surface of the demister with a wastewater
derived from a well source.
19. The method as recited in claim 13, further comprising blowing
heated air into the air flow path.
20. The method as recited in claim 13, further comprising:
generating electrical power using an electrical generator to
produce an exhaust stream; supplying the electrical power to a
power grid and/or powering a control unit configured to operate the
electrical generator; using the exhaust stream to create at least a
portion of the flowing air stream.
21. The method as recited in claim 13, further comprising
regulating the speed of the flowing air stream based on the
temperature or humidity within or outside of the housing.
22. A method for evaporating fluid, the method comprising:
obtaining wastewater from a well source, the wastewater containing
VOCs; collecting at least a portion of the VOCs from the
wastewater; pooling the wastewater having the at least a portion of
the VOCs removed therefrom within a reservoir that is bounded by a
housing, the housing also bounding an air flow path that is
disposed over top of and that communicates with the reservoir, the
air flow path extending from an air inlet opening in the housing to
an air outlet opening in the housing; creating a flowing air stream
wherein air in the environment outside of the housing flows into
the air flow path through the air inlet opening, travels along the
air flow path so that the air passes over the wastewater within the
reservoir, and then exits out of the housing through the air outlet
opening; spraying the wastewater within the reservoir into the air
flow path within the housing and above the reservoir; burning the
VOCs collected from the wastewater in a thermal oxidizer so that
the thermal oxidizer produces an exhaust; and delivering the
exhaust of the thermal oxidizer into the air flow path within the
housing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/285,870, filed Dec. 11, 2009, the disclosure of
which is incorporated herein by specific reference.
BACKGROUND OF THE INVENTION
[0002] 1. The Field of the Invention
[0003] The present invention relates to wastewater treatment
systems and methods that utilize a water evaporator for separating
wastewater from salts, minerals, and/or oil and/or gas.
[0004] 2. The Relevant Technology
[0005] As natural gas is extracted from a ground well, a
significant quantity of water accompanies the natural gas. This
water is typically separated from the natural gas at a location
proximate to the well head and then stored in an adjacent tank.
Because of contaminants within the water, the water is typically
trucked to a licensed disposal facility where it is deposited in a
lined pond for evaporation. This same operation also typically
occurs in the production of oil wells. That is, a significant
quantity of water will often accompany extracted oil. The water and
oil are deposited in a settling tank where the water and oil are
separated. The water is then typically trucked to a licensed
disposal facility where it is deposited in a lined pond for
evaporation. Evaporation of the collected water is typically
enhanced by sprinkler systems that spray the water into the air
over the pond.
[0006] Although the above process is functional, there are
significant costs in having to repeatedly ship the water to the
disposal facility. There are also significant costs charged by the
disposal facility to accept the water. Furthermore, trying to
dispose of water through an evaporation pond can be problematic.
For example, under windy conditions the sprinkler system cannot be
operated due to the risk of non-evaporated fluid being carried by
the wind onto the surrounding area. Furthermore, during colder or
high humidity conditions, evaporation may fall below a desired
evaporation rate.
[0007] Accordingly, what is needed are systems that eliminate or
minimize the above problems or shortcomings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Various embodiments of the present invention will now be
discussed with reference to the appended drawings. It is
appreciated that these drawings depict only typical embodiments of
the invention and are therefore not to be considered limiting of
its scope.
[0009] FIG. 1 is an elevated side view of one embodiment of an
inventive wastewater treatment system that includes a water
evaporation system in fluid communication with a well source and
storage and separation system;
[0010] FIG. 2 is a front perspective view of the water evaporation
system shown in FIG. 1;
[0011] FIG. 3 is a rear perspective view of the water evaporation
system shown in FIG. 1;
[0012] FIG. 4 is a cutaway front perspective view of the water
evaporation system shown in FIG. 1;
[0013] FIG. 5 is a cutaway rear perspective view of the water
evaporation system shown in FIG. 1;
[0014] FIG. 6 is a cross sectional front view of the evaporation
chamber of the water evaporation system shown in FIG. 1;
[0015] FIG. 7 is a partially cutaway perspective view of the water
evaporation system shown in FIG. 1 depicting a fan disposed within
the stack;
[0016] FIG. 8 is a perspective view of the storage compartment of
the water evaporation system shown in FIG. 1;
[0017] FIG. 9 is a schematic of a wastewater treatment system
according to an alternative embodiment of the invention;
[0018] FIG. 10 is a perspective view of an alternative embodiment
of a water evaporation system;
[0019] FIG. 11 is a cutaway perspective view of a first portion of
the evaporation system shown in FIG. 10;
[0020] FIG. 12 is a cutaway perspective view of a second portion of
the evaporation system shown in FIG. 10;
[0021] FIG. 13 is an embodiment of a pretreatment system of the
wastewater treatment system shown in FIG. 1;
[0022] FIG. 14 is a cross section of a separation unit of the
pretreatment system shown in FIG. 13 during operation;
[0023] FIG. 15 is a cross section of a separation unit of the
pretreatment system shown in FIG. 13 during a foam clean out stage;
and
[0024] FIG. 16 is a cross section of a separation unit of the
pretreatment system shown in FIG. 13 during a solids cleanout
stage.
DETAILED DESCRIPTION
[0025] The present invention relates to wastewater treatment
systems and methods for treating wastewater streams. The wastewater
treatment systems include a water evaporator that reduces the
volume of the wastewater. The wastewater treatment systems can also
include additional components or systems to perform one or more of
the following features: separating components of the wastewater
stream, collecting the evaporated water, generating electrical or
mechanical power, and/or utilizing low-value hydrocarbons in a cost
effective and environmentally friendly manner.
[0026] The water evaporation systems include a housing assembly
providing a fluid reservoir and bounding an air flow path. A
misting system is configured to spray wastewater from the fluid
reservoir into the air flow path. A portion of the wastewater is
evaporated, thereby concentrating salts and/or minerals in the
fluid reservoir. The concentrated waste can be efficiently handled
and/or disposed of.
[0027] The wastewater treatment systems include one or more sources
of heat, which is delivered through the air flow path of the
housing assembly to enhance evaporation. In various embodiments of
the invention, the wastewater treatment system can include
generators, motors, thermal oxidizers, gas furnaces, and the like
to generate heat and/or create an airstream that can evaporate
substantial quantities of water. The use of these components can
produce a synergistic benefit that enhances the environmentally
favorable treatment and disposal of a wastewater stream.
[0028] In some embodiments of the invention, the evaporation system
can include one or more demisters near the air outlet of the
evaporation system to remove suspended water droplets. The
demisters remove suspended water without preventing expulsion of
the evaporated water, thereby reducing amount of salt, metals, and
other dissolved materials that escape through the airstream.
[0029] Some embodiments of the invention may also include a
pretreatment system for separating hydrocarbons and wastewater to
further facilitate efficient evaporation of the wastewater in the
water evaporator.
[0030] In yet other embodiments, the water treatment systems can
include condensers downstream from the evaporation system to
condense the evaporated water from the air stream to produce
desalinated and/or potable water.
[0031] Although the water treatment systems can be used in a
variety of different situations where it is desirable to evaporate
a large quantity of water, the present invention will often be used
in association with the oil and gas industry. Some embodiments of
the invention may be particularly advantageous when carried out at
or near the oil and/or gas well.
[0032] Depicted in FIG. 1 is one embodiment of a wastewater
treatment system 100 incorporating features of the present
invention. In general, wastewater treatment system 100 comprises a
well source 212 that operates in conjunction with a storage and
separation system 214 and a water evaporation system 210. Well
source 212 can be part of an oil or gas well. Well source 212 can
include any number of wells; and, where two or more wells are
provided, the wells can extract the same or different hydrocarbons.
The hydrocarbons in well source 212 include wastewater. The
wastewater from well source 212 may include emulsified hydrocarbons
and/or dissolved minerals and/or salts. The concentration of the
hydrocarbons, salts, minerals, and/or other contaminants in the
wastewater from well source 212 are typically sufficient to
preclude free release of the wastewater into the environment
without proper treatment. In an alternative embodiment, well source
212 may be brackish water such as sea water, where the desired
separation is the separation of water from dissolved salts to
produce condensed, desalinated water.
[0033] During production of well source 212, fluids such as water
and oil are passed out of well source 212 and are delivered, either
directly or indirectly, to storage and separation system 214.
Storage and separation system 214 can be an underground storage
tank and/or above ground storage tanks. Storage and separation
system 214 can include a single tank or two or more tanks in series
and/or in parallel. In one embodiment, storage and separation
system 214 can include a separation apparatus that separates crude
hydrocarbons into a wastewater stream and hydrocarbon products.
Within storage and separation system 214, the water and oil
separate with the oil rising to the top and the water settling to
the bottom. A pipe 218 is then used to convey the wastewater from
storage and separation system 214 to water evaporation system 210.
The water can be conveyed either under the force of gravity or by
the use of a pump 219. As discussed below in greater detail, water
evaporation system 210 is then used to evaporate the water and
disperse it into the surrounding environment. If desired, a flow
meter 221 can be mounted on pipe 218 so as to provide an exact
measurement of how much fluid has been evaporated through water
evaporation system 210.
[0034] It is appreciated that the water can be delivered to water
evaporation system 210 using a variety of different methods. For
example, in contrast to storage and separation system 214 being
fluid coupled with a well head, the fluid can be delivered to
storage and separation system 214 by truck, rail, or other
transport mechanism. Furthermore, in contrast to water evaporation
system 210 being coupled with storage and separation system 214,
the water can be delivered to water evaporation system 210 directly
from a settling pond or other type of container system. Likewise,
the water can be delivered to water evaporation system 210 directly
from a truck, rail car, or other type of vehicle.
[0035] The wastewater is delivered to evaporation system 210 to
have its mineral content concentrated. Concentrated waste 126 can
then be more economically disposed of. In one embodiment,
wastewater stream 106 and/or 120 is delivered to evaporation system
210 with a total dissolved solids content in a range from about 1%
to about 15%, more typically in a range from about 2%-10%. The
concentrated waste 126 has a higher mineral concentration. In one
embodiment, the total dissolved solids of concentrated waste 126
may be in a range from about 10% to about 70%, more typically in a
range from about 15% to about 50%.
[0036] Turning to FIG. 2, water evaporation system 210 comprises a
housing assembly 211. Housing assembly 211 can include an
evaporator housing 220 having a substantially parallelepiped
configuration that includes a substantially flat roof 322 and an
opposing floor 324 that each extend between a first end 325 and an
opposing second end 327. An encircling sidewall 326 extends between
roof 322 and floor 324. Encircling sidewall 326 includes a first
sidewall 228 and an opposing second sidewall 330 that each extend
between a first end wall 332 and an opposing second end wall 334.
In the embodiment depicted, housing 220 is elongated with a central
longitudinal axis extending between first end wall 332 and second
end wall 334. In alternative embodiments, housing 220 need not be
elongated. Likewise, housing 220 need not have a parallelepiped
configuration. For example, roof 322 can be pitched as opposed to
being flat. Hooking ports 336 are formed on a plurality of the
corners of housing 220 and are typically formed on all eight
corners of housing 220. Hooking ports 336 comprise small openings
which can receive hooks, straps, or fasteners for lifting,
transporting, or securing housing 220.
[0037] In one embodiment, housing 220 comprises a standard metal
shipping container having standard dimensions that has been
modified for the intended use of the present invention. For
example, standard metal shipping containers intended for
intercontinental use typically have external standard dimensions of
length 20 feet (6.10 m), 30 feet (9.14 m), or 40 feet (12.20 m);
width of 8 feet (2.44 m); and height of 8.5 feet (2.59 m) or 9.5
feet (2.90 m). These dimensions are only approximations and can
vary within a few inches, such as within six inches (0.15 m). For
example, the 30 feet containers are typically closer to 29.9375
feet (9.125 m) in length. Other standard and non-standard
dimensions can also be used. In the illustrated example of the
present invention, housing 220 has a length of 40 feet (12.20 m), a
width of 8 feet (2.44 m), and height between 8.5 feet (2.59 m) to
9.5 feet (2.90 m) each within a tolerance of six inches (0.15
m).
[0038] By forming housing 220 out of standard shipping containers,
housings 220 can be stacked, if desired, and easily transported by
rail, ship, truck or the like using conventional techniques. In an
alternative embodiment, housing 220 can be custom designed having
other dimensions and configurations and can be made from other
materials such as wood, plastic, fiberglass, composite, and the
like.
[0039] Depicted in FIGS. 2 and 3, a support 338 is mounted on floor
324 at second end 327 so as to downwardly project from floor 324.
Support 338 typically has a height "h" in a range between about 15
cm to about 90 cm with about 20 cm to about 45 cm being more
common. Other heights can also be used or support 338 can be
eliminated. Support 338 can be mounted to housing 220 by welding,
fasteners, or other conventional techniques. As will be discussed
below in greater detail, support 38 functions to elevate second end
327 such that when housing 220 is disposed on a flat surface, floor
324 downwardly slopes from second end 327 to first end 325. In
alternative embodiments, support 338 need not be directly mounted
to floor 324 but can merely be positioned beneath floor 324 when
positioning housing 220.
[0040] As depicted in FIG. 4, housing 220 has an interior surface
340 that bounds a chamber 568. A partition wall 565 is disposed
within chamber 568 at or towards first end 325 so as to divide
chamber 568 into an evaporation chamber 566 disposed towards second
end 327 and a storage chamber 68 disposed towards first end 325.
Partition wall 565 typically extends from roof 322 to floor 324 and
between opposing walls 228 and 330. However, partition wall 565
need not extend all the way to roof 322 and/or openings can be
formed through partition wall 565.
[0041] As depicted in FIG. 2, a plurality of spaced apart access
ports 344 extend through a first sidewall 228 and second sidewall
330 so as to communicate with evaporation chamber 566. Access ports
344 are typically positioned at a height of at least about 1 meter
above floor 324 (although other heights can also be used) and are
sized to enable an individual to reach therethrough for accessing
spray nozzles, as will be discussed below in greater detail, that
are positioned within evaporation chamber 566. Each access port 344
can have a corresponding door 343 mounted on first sidewall 228 and
second sidewall 330 for selectively closing and, if desired,
locking access ports 344. Doors 348 and 349 can be hingedly,
slidably, or removably mounted to the sidewalls. In alternative
embodiments, it is appreciated that access ports 344 and doors 348
and 349 can be eliminated so that no openings are formed in the
sidewalls.
[0042] As depicted in FIG. 3, a doorway 347 is formed on second end
wall 334 to permit selective entrance into evaporation chamber 566.
The bottom of doorway 347 is typically elevated a distance above
floor 324 to help retain fluid within evaporation chamber 566. A
door 348 can be hingedly mounted on second end wall 334 to permit
selective closure of doorway 347. In alternative embodiments,
doorway 347 can be eliminated and replaced with an access opening
formed at some other location on housing assembly 211.
[0043] With reference to FIG. 2, a doorway 347 can be formed on
first end wall 332 for accessing storage chamber 568 at first end
325. A pair of opposing doors 348 and 349 are shown mounted on
first end wall 332 for selectively closing doorway 347. Doors 348
and 349 have a plurality of slots 350 extending therethrough so
that air can pass from the surrounding environment into storage
chamber 568 by passing through slots 350. As will be discussed
below in greater detail, it is desirable to have a fresh air inlet
to storage chamber 568 so as to help control the temperature
therein and to provide combustion air for the generator, furnace,
and/or other mechanics that can be positioned within storage
chamber 568. In alternative embodiments, slots 350 can be replaced
with or supplemented by other openings formed in doors 348 and 349,
first end wall 332, sidewalls 228 and 330 and/or roof 322 for
providing air to storage chamber 568.
[0044] An inlet opening 352 extends through roof 322 so as to
communicate with evaporation chamber 566 at first end 325 while an
outlet opening 354 extends through roof 322 so as to communicate
with evaporation chamber 566 at second end 327. As will be
discussed below in greater detail, housing assembly 211 can include
a tubular stack 356 mounted on roof 322 so as to be disposed over
outlet opening 354. Stack 356 has an interior surface 358 bounding
a passage 360 extending between an upper end 362 and an opposing
lower end 364. Upper end 362 provide an outlet opening for housing
assembly 211. Stack 356 typically has a height extending between
the opposing ends in a range between about 1 meter to about 30
meters with about 2 meters to about 5 meters being more common.
Other lengths can also be used. In one embodiment, stack 356 can be
hingedly mounted to roof 322 so that stack 356 can be selectively
folded over to rest on top of roof 322 during transport of housing
210 and then folded upward and secured in position for final
use.
[0045] Returning to FIG. 4, evaporation chamber 566 generally
comprises a fluid reservoir 572 and an air flow path 574. More
specifically, fluid reservoir 572 is bounded by floor 324 and the
lower end of first sidewall 228, second sidewall 230, second end
wall 334, and partition wall 65. These structural elements are
secured together and are typically covered with a sealant so as to
minimize rust and be substantially water tight. As a result, a
fluid 576 can be pooled within fluid reservoir 572, the pool of
fluid 576 having a top surface designated by a line 578. In
alternative embodiments, various types of liners or one or more
large containers can be positioned on or adjacent to floor 324 so
as to form fluid reservoir 572.
[0046] As previously discussed with regard to FIG. 1, fluid 576 is
delivered to fluid reservoir 572 thorough a pipe 218 fluid coupled
with housing 220. It is again appreciated that fluid 576 can be
delivered to fluid reservoir 572 in a variety of different ways
such as through a hose, tube, pipe, or even through an opening in
housing 220 through which fluid 576 is poured. It is also noted
that fluid 576 can be delivered to fluid reservoir 572 through any
surface of housing assembly 211. In the embodiment depicted, fluid
576 is delivered to fluid reservoir 572 through first sidewall 228
at second end 327 of housing 220. As a result of support 338, floor
324 slopes downwardly toward partition wall 565. Accordingly, once
fluid 576 enters fluid reservoir 572, fluid 576 flows down toward
partition wall 565. In an alternative embodiment, all or a portion
of fluid reservoir can be stored in a separate compartment of
housing assembly 211. However, providing fluid reservoir 572 on a
floor of housing 220 minimizes storage costs and improves
evaporation.
[0047] In one embodiment of the present invention, means are
provided for filtering fluid 576. By way of example and not by
limitation, a weir 586, as shown in FIG. 4, upwardly projects from
floor 324 and extends between opposing sidewalls 228 and 330. Weir
586 can be located at any position between partition wall 565 and
second end wall 334 but is typically disposed closer to partition
wall 565. Before reaching partition wall 565, fluid 576 must pass
over weir 586. As a result, weir 586 helps to retains solids and
other particulate matter on the upstream side of weir 586, thereby
filtering fluid 576. In alternative embodiments, two or more spaced
apart weirs can be formed on floor 324. One or more holes can be
formed through the one or more weirs so that the fluid can pass
therethrough but larger solids are preventing from passing
therethrough. In still other embodiments, sections of screens or
other filtering material can be positioned to extend between
opposing sidewalls 228 and 330 so as to screen and thereby filter
the fluid as is passes therethrough. Other conventional filtering
techniques can also be used. Door 446 can be used to periodically
access fluid reservoir 572 for cleaning out solids that have
collected therein. In alternative embodiments, it is appreciated
that support 338 can be eliminated and that floor 324 can be
horizontally positioned. This is especially true where the fluid is
filtered before entering fluid reservoir 572 or where filtering
techniques other than weir 586 are used.
[0048] Air flow path 574 comprises the area within the evaporation
chamber 566 that is vertically above fluid reservoir 572.
Accordingly, from one perspective, the boundary between air flow
path 574 and reservoir 572 can be top surface 578 of pooled fluid
576. That is, the area above top surface 578 is air flow path 574
while the area below top surface 578 is fluid reservoir 572. As top
surface 578 raises within evaporation chamber 566, the volume of
fluid reservoir 572 increases while the volume of air flow path 574
decreases.
[0049] With continued reference to FIG. 4, inlet opening 352
extends through roof 322 so as to communicate with first end 325 of
evaporation chamber 566/air flow path 574 while outlet opening 354
extends through roof 322 so as to communicate with second end 327
of evaporation chamber 566/air flow path 574. A baffle 580 projects
into air flow path 574 at a location between inlet opening 352 and
outlet opening 354 so as to constrict the area of air flow path 574
thereat. In the embodiment depicted in FIG. 6, baffle 580 comprises
a plate that downwardly projects from the interior surface of roof
322 so as to extend substantially orthogonal thereto. In
alternative embodiments, baffle 580 can extend so as to form an
inside angle between baffle 580 and roof 322 in a range between
about 40.degree. to about 140.degree. with about 60.degree. to
about 120.degree. being more common. Other angles can also be used.
Baffle 80 can also be mounted to roof 322 by a hinge 583 so that
baffle 580 can be selectively rotated out of the way for accessing
evaporation chamber 566 or for positioning baffle 580 at a desired
angle for controlling air flow past baffle 580.
[0050] In the embodiment depicted baffle 580 has a substantially
rectangular base portion 582 extending between opposing sidewalls
228 and 330 and a substantially triangular portion 84 that extends
from base portion 782 down to an apex 786 that is centrally
positioned between opposing sidewalls 228 and 330. It is
appreciated that baffle 580 can come in a variety of different
sizes, shapes, and configurations. Examples include, but are not
limited to baffles having a substantially triangular, semicircular
or semielliptical configuration, or a substantially square or
rectangular configuration. Baffle 580 can be positioned above top
surface 578 of pooled fluid 576. Alternatively, baffle 580 or any
of the other baffles can be formed from a porous material or have a
plurality of openings 581 that extend therethrough so that the air
and moisture can pass therethrough. In this embodiment, the baffle
can extend down into pooled fluid 576. It is also noted that baffle
80 need not be a flat plate but can be contoured and/or can have a
uniform or varied thickness.
[0051] In one embodiment of the present invention, means are
provided for regulating the level of fluid 576 within fluid
reservoir 572. By way of example and not by limitation, a sensor
630 (FIG. 5) is mounted on partition wall 565 within evaporation
chamber 566 and is electrically coupled with pump 219 (FIG. 1). In
one embodiment, sensor 630 comprises a float sensor wherein when
top surface 578 of pooled fluid 576 drops below a certain level,
pump 501 is activated and fluid 576 is pumped into fluid reservoir
572. When top surface 578 of pooled fluid 576 reaches the desired
level, sensor 630 turns pump 501 off. It is appreciated that sensor
630 can be positioned at any location that will enable it to sense
the level of pooled fluid 576 and that sensor 630 can comprise any
type of sensor, such an electrical eye, pressure sensor, or the
like, that can determine the level of pooled fluid 576.
[0052] Returning to FIGS. 4 and 5, means are provided for misting
or spraying fluid 576 pooled within fluid reservoir 572 into air
flow path 574 between baffle 580 and inlet opening 352. By way of
example and not by limitation, piping 588 is disposed within
evaporation chamber 566 and generally extends between partition
wall 565 and baffle 580. More specifically, piping 588 comprises a
first pipe section 590 that extends along the interior of first
sidewall 528 while a second pipe section 592 extends along the
interior of second sidewall 30. Both pipe sections generally
extending between partition wall 565 and baffle 580 but can extend
beyond baffle 580. As depicted in FIG. 6, brackets 594 are used to
secure pipe sections 590 and 592 to their corresponding sidewalls
so that the pipe sections are inwardly set a distance from the
sidewalls. Longitudinally spaced along pipe sections 590 and 592
are a plurality of spray nozzles 596. Spray nozzles 596 are
position and oriented so that fluid entering the pipe sections is
outwardly and upwardly sprayed through spray nozzles 596. Returning
to FIG. 4, a pipe section 698 extends between first and second pipe
sections 590 and 592 so as to provide fluid communication
therebetween.
[0053] Disposed within storage chamber 568 is a pump 501. As shown
in FIG. 3, pump 501 has an inlet pipe 502 that extends through
partition wall 565 so as to be in fluid communication with fluid
reservoir 572. Pump 501 also has an outlet pipe 504 that extends
through partition wall 565 so as to be in fluid communication with
piping 588. During operation, pump 501 draws in fluid 576 from
fluid reservoir 572 and pumps it out into piping 588. Fluid 576
exits piping 588 through spray nozzles 596 wherein fluid 576 sprays
upwardly within air flow path 574 and then travels downward back
into fluid reservoir 572 where the cycle then continues. To
optimize spraying of fluid 576, spray nozzles 596 are positioned
above top surface 578 of pooled fluids 576.
[0054] As will be discussed below in greater detail, at least a
portion of fluid 576 sprayed within air flow path 574 evaporates
and is removed out of air flow path 574. By having fluid 576
sprayed upward and then fall back down, the duration that the
sprayed fluid 576 is suspended within air flow path 574 is
maximized so as to maximize evaporation of fluid 576 within air
flow path 574. In an alternative embodiment, fluid 576 can simply
be sprayed down from roof 322.
[0055] It is appreciated that the means for spraying fluid 576
pooled within fluid reservoir 572 can have a variety of different
configurations. By way of example and not by limitation, it is
appreciated that piping 588 can be mounted on or below floor 324
and/or on or above roof 322. Elongated risers can then be used to
position spray nozzles 596 at the desired position within air flow
path 574. In contrast to having two pipe sections 590 and 592, it
is appreciated that a single pipe section can be used that is
either centrally positioned between or is positioned along one of
the sidewalls. Alternatively, three or more spaced apart pipe
sections can be used. It is likewise appreciated that the, type,
size, configuration, number, orientation, and position of spray
nozzles 596 can be dramatically varied. The general concept is to
spray fluid 576 into air flow path 574 at a flow rate and
concentration that will maximize the evaporation of fluid 576
within air flow path 574.
[0056] In one embodiment of the present invention, means are
provided for drawing air from the surrounding environment into air
flow path 574 through inlet opening 352 and for drawing the air out
of air flow path 574 through outlet opening 354. By way of example
and not by limitation, depicted in FIG. 7 is a fan 810 disposed
within passage 360 of stack 356 at lower end 364 thereof. During
operation, fan 810 draws air up and out of air flow path 574 which
then passes through passageway 360 of stack 356 and then out into
the surround environment. As air is drawn out of air flow path 374
by fan 810, a low pressure is created within air flow path 574
which causes air from the surrounding environment to be drawn into
air flow path 574 through inlet opening 352, as shown in FIG. 4. As
such, during operation of fan 810, air from the surrounding
environment is continually being drawn from the surrounding
environment into air flow path 574 through inlet opening 352. The
air then travels along the length of air flow path 374 over top of
fluid reservoir 372, passes around baffle 580, and then travels up
and out to the surrounding environment through stack 356.
[0057] It is appreciated that a variety of different types of fans
can be used within stack 356 or outlet opening 354 for drawing the
air out of air flow path 574. In alternative embodiments, it is
appreciated that a fan can be positioned at or adjacent to inlet
opening 352 for drawing air into air flow path 574 or pushing air
into airflow path 354. Likewise, in contrast to forming inlet
opening 352 on roof 322, inlet opening 352 can also be formed on
partition wall 565 and receive air through slot 350 or the
alternatives thereto as previously discussed. Inlet opening 352 can
also be formed on sidewall 228 or 330. Similarly, outlet opening
354 can be formed on sidewall 228 or 330 or end wall 334. In these
embodiments, stack 356 would have a 90.degree. elbow to connect
with outlet opening 354.
[0058] During operation, a continuous flow of fresh air is drawn in
from the environment and passed between inlet opening 352 and
outlet opening 354 along air flow path 574. Spraying fluid 576
within air flow path 574 between inlet opening 352 and baffle 380
causes the air flow in that region to be highly turbulent. The
combination of spraying fluid 576 in a fresh air stream that is
highly turbulent and that is heated within air flow path 574 due to
the ambient temperature and radiant energy striking housing 220
serves to optimize the evaporation of sprayed fluid 576 within air
flow path 574.
[0059] Baffle 580 and stack 356 help to facilitate removal of
non-evaporated water droplets from the air flow before the air flow
exits stack 356 and travels back into the surrounding environment.
This is to help ensure that water droplets do not simply pass out
through stack 356 and then deposit on the ground surrounding
housing 220. With regard to baffle 580, spray nozzles 596 typically
do not extend past baffle 580 so that the air flow between baffle
580 and outlet opening 354 is less turbulent than between inlet
opening 352 and baffle 580. Baffle 580 thus in part functions as a
shield to help minimize the amount of sprayed fluid that is passed
beyond baffle 580 and thus decrease air turbulence beyond baffle
580. Baffle 580 also partially constricts that area of air flow
path 574 at the location of baffle 580. By constricting air flow
path 574, the air flow becomes more laminar as it travels around
baffle 580. Likewise, the air flow increases in speed as it travels
through the area constricted by baffle 580 but then slows down as
it expands into the larger space on the opposing side of baffle
580. As a result of producing a slower, less turbulent air flow,
fluid droplets that are carried by the air flow but that have not
yet evaporated, drop out of the air flow and back into fluid
reservoir 572. Stack 556 provides added retention time for the air
flow to help ensure that substantially all of the non-evaporated
fluid droplets fall out of the air flow before the air flow exits
stack 556. Furthermore, by being vertically oriented, the fluid
droplets falling out of the air flow fall through the upcoming air
flow so as to combine with and collect other fluid droplets.
[0060] On occasion, such as during the colder months of the year or
during a short term cold period, the ambient temperature and
radiant energy produced by the sun may not be sufficient to
facilitate evaporation of fluid 576 at a desired rate. Accordingly,
in one embodiment of the present invention, means are provided for
blowing heated air into air flow path 574. By way of example and
not by limitation, a furnace 514 is disposed within storage chamber
568. Furnace 514 comprises a heating element and a fan. A tubular
vent 926 extends from furnace 514 through partition wall 565 into
air flow path 572. Furnace 514 can be designed to operate on
electricity, gasoline, natural gas and/or propane or other fuels.
For example, natural gas from well head 112 can be used to operate
furnace 514.
[0061] Turning to FIG. 8, a central processing unit (CPU) 920 can
be used to operate and selectively control various mechanics of
water evaporation system 210. For example, CPU 120 is electrically
coupled with sensors 922. Sensors 922 can comprise humidity
sensors, temperature sensors, wind sensors, pressure sensors, and
other sensors that can be used in optimizing the operation of
evaporation system 10. Sensors 122 can be positioned within storage
chamber 568, outside of housing 220, and/or within evaporation
chamber 566. Based on information such as the relative humidity and
temperature, CPU 920 can selectively control the speed of fan 810,
the flow rate of pump 501, and/or the operation of furnace 514. By
selectively controlling and changing the operation of these
mechanics, evaporation of fluid 576 can be optimized within
evaporation chamber 566. For example, as the humidity in the
surrounding environment increases, such as when raining, it may be
necessary to slow down the speed of fan 810 and/or the flow rate of
pump 501 so that water droplets are not passed out through stack
556. CPU 920 can also facilitate controlled operation of pumps 219
and 501, furnace 514, fluid level sensor 630 and fan 810.
[0062] Returning to FIG. 8, a generator 924 can be positioned
within storage chamber 68. Generator 924 can be used to help
facilitate operation of the various electrical components such as
pumps 219 and 501, CPU 920, sensors 922 and 630, furnace 514, fan
810 and the like. A vent 926 extends through partition wall 565 to
deliver exhaust from generator 924 to evaporation chamber 566 so as
to help increase the temperature therein.
[0063] It is appreciated that the above discussion is only one
embodiment of how water evaporation system 100 can be configured
and that the various components can be moved around. For example,
by making plumbing modification, it is appreciated that baffle 580
and stack 556 can be positioned toward partition wall 565 while
inlet opening 352 and spray nozzles 596 are positioned toward
second end wall 334.
[0064] The present invention also envisions a variety of other
embodiments of wastewater treatment systems. For example, depicted
in FIG. 9 is one embodiment of a wastewater treatment system 100A
wherein like features between wastewater treatment system 100 and
100A are identified by like reference characters.
[0065] Wastewater treatment system 100A includes well source 212.
Hydrocarbons extracted from well source 212 can be delivered via
pipe 216 to be stored in storage and separation system 214.
Hydrocarbons are separated in storage and separation system 214 to
produce a wastewater stream 106 and hydrocarbon products 108.
Storage and separation system 214 may also provide for separating
volatile organic compounds (VOCs) 110 from wastewater stream 106
and hydrocarbon products 108. As explained in more detail below,
the VOCs can be used to generate heat in a thermal oxidizer
114.
[0066] In one embodiment wastewater stream 106 may optionally be
delivered to a pretreatment system 116 for additional separation.
Pretreatment system 116 is described more fully below with respect
to FIGS. 13-16. Pretreatment system 116 separates out emulsified
and/or dissolved hydrocarbons 122 and solids 124, to produce a
pretreated wastewater stream 120. Pretreated wastewater stream 120
can be supplied to a water evaporation system 210A to be reduced in
volume and its impurities concentrated. Treated, concentrated
wastewater is removed from water evaporation system 210A as vapor
and concentrated waste 126. In one embodiment, concentrated waste
126 may be a slurry.
[0067] Wastewater treatment system 100A further includes one or
more sources of heat for increasing the rate of evaporation of the
wastewater in water evaporation system 210A. In one embodiment, the
source of heat can be a thermal oxidizer 114 configured to oxidize
volatile organics 110 from storage and separation system 214 and/or
pretreatment system 116 and/or gas from well 212. In an alternative
embodiment, methane and/or another type of hydrocarbon from well
source 212 can be delivered through a pipe 128 to a furnace 514A
and/or a generator 924A, where the fuel can be burned to produce
heat, air flow, mechanical power, and/or electricity. The heat from
furnace 514A and/or generator 924A can be delivered to water
evaporation system 210A to facilitate the evaporation of
wastewater. Generator 924A may also be connected to a power grid
134 and used to generate electrical power for grid 134.
[0068] In one embodiment, a significant portion of the heat
generated for water evaporation system 210A can be a waste heat.
The term "waste heat" includes heat derived from electrical
generation and/or the burning or oxidizing of hydrocarbons that are
of little value due to their impurity and/or cost of handling. For
example, waste heat includes heat derived from the exhaust of an
electrical generator and/or the thermal oxidation of volatile
organic compounds, but does not include heat generated from burning
pipeline quality gas in a furnace. In one embodiment, at least
about 20% to about 100% of the total heat generated and input into
water evaporation system 210 is a waste heat, more specifically
about 30% to about 95%, and even more specifically 50% to about
90%. In one embodiment, at least about 30%-100% of the heat is
produced from a turbine (i.e., non-reciprocating) engine, more
specifically about 50% to about 70%. In one embodiment, about
10%-70%, of the heat is produced from a reciprocating engine, more
specifically about 30% to about 50%. In one embodiment about 20% to
about 100% is generated from a non-engine process such as a furnace
or thermal oxidizer, more specifically about 30% to about 80%.
[0069] Any type of thermal oxidizer 114 may be used in system 100A
so long as the thermal oxidizer is compatible with the hydrocarbon
source being oxidized. Examples of suitable thermal oxidizers
include regenerative thermal oxidizers, regenerative catalytic
oxidizer thermal recuperative oxidizer, catalytic oxidizer, and/or
direct fired thermal oxidizer (i.e. afterburner). The heat from the
thermal oxidizer can be piped directly into water evaporation
system 210A or can be used to heat wastewater stream 120 in a heat
exchanger. Those skilled in the art are familiar with selecting
thermal oxidizers that can efficiently create a hot air stream
and/or heat a fluid in a heat exchanger. The use of thermal
oxidizer 114 not only provide heat for the rapid evaporation of
wastewater but it also efficiently and safely disposes of unwanted
VOCs.
[0070] System 100A may also include furnace 514A as described
above. Furnace 514A can be operated using natural gas or another
hydrocarbon source. The hydrocarbon source can be purified,
partially purified, unpurified, refined, and/or unrefined. Furnace
514A is typically configured and/or positioned within or adjacent
water evaporation system 210 to maximize heat transfer to the air
flow in evaporation system 210. For example, in one embodiment
furnace 514A can have the same size and relative placement as
furnace 514 as previously discussed with regard to FIG. 4. In
alternative embodiments, furnace 514A can be disposed outside of
water evaporator system 210A with the exhaust being piped into
system 210. In one embodiment, furnace 514A can have a size in a
range between about 5 million BTU to about 50 million BTU with
about 10 million BTU to about 20 million BTU being more common.
Other sizes of furnaces can also be used. Those skilled in the art
are familiar with furnaces that can efficiently transfer heat to
the air flow path.
[0071] Generator 924A can comprise any type of electrical
generator. For example, generator 924A may be an internal
combustion engine or a micro turbine. Generator 924A can be
configured to generate electrical power for transferring to power
grid 134. Thus, generator 924A can be used to convert the natural
gas from well source 212 to electricity which can then be
transferred onto power grid 134. This eliminates the need for
creating a gas line that transfers the gas to an established
collection line. In addition to or in the alternative, generator
924A can be configured to generate the electricity necessary to
power all the electrical components and mechanical components of
water treatment system 100A. For example, generator 924A can drive
a compressor, pump, a control unit and various valves. Thus,
generator 924A can comprise generator 924 as previously discussed
with regard to FIG. 8. In one embodiment the power generated by
generator 924A may be used to pump hydrocarbons from well source
212 and/or to pressurize hydrocarbons for cleaning in a gas
conditioner and/or for transportation in a gas line. Thus,
generator 924A may be substituted for or additionally include an
engine and/or pumps that generate pressure with or without the use
of electricity. Operating a natural gas driven pump to directly
pipe gas into a gas line can be highly efficient since the exhaust
from operating the gas-powered pump can be scrubbed in evaporation
system 210. Those skilled in the art are familiar with generators,
engines, turbines, and pumps suitable for generating electrical
and/or mechanical power that can be utilized in system 100A.
[0072] Wastewater treatment system 100A may also include a control
unit 136 housing electrical components configured to control any of
the components of system 100A. In one embodiment, control unit 136
includes hardware and/or software for operating one or more of
fans, pumps, valves, motors, turbines, sensors, and the like to
maintain and/or change the state of system 100A. In one embodiment,
control unit 136 includes CPU 920 and software that monitors the
state of the system through sensors 922 (FIG. 8), fluid level
sensor 630 (FIG. 5), and or sensors 1280, 1282, 1284, 1286 (FIG.
12). The software may include computer executable instructions
configured to change the state of equipment in the system to
maintain the system within one or more operating parameters. For
example, generator 924A, thermal oxidizer 114, and/or furnace 514A
may be operated alone or in combination with a fan or other blower
to maintain the temperature and/or humidity of the air flow in
evaporation system 210A with a desired range.
[0073] Generator 924A can be sized and configured to produce a
desired amount of heat for evaporation system 210A and/or to
generate a desired amount of electrical power. As discussed above,
in one embodiment, the electrical generator can be sized and
configured to provide sufficient power for running the electrical
systems of system 100A, including the control unit 136. This
arrangement can be advantageous where the well source 212 is not
near a power transmission line. In this embodiment, additional heat
sources (e.g., thermal oxidizer, gas furnace, etc.) may be needed
to provide sufficient heat for evaporation system 210A.
[0074] Alternatively, or in addition, one or more generators 924A
can be configured to generate excess power for a grid, in which
case, the power generation can greatly exceed the power needs of
system 100A and the heat value of the exhaust can provide a
substantial percentage and/or all of the heat in water evaporation
system 210A. In one embodiment, one or more generators 924A used in
system 100 have a total power output in a range from about 250 kW
to about 20 MW, more specifically in a range from about 1 MW to
about 15 MW, and even more specifically in a range from about 2 MW
to about 10 MW. In an alternative embodiment, one or more
generators can be sized to produce an exhaust coupled to the
evaporation system 210A and providing at least about 30% to about
100% of the total heat input to evaporation system 210A, more
specifically about 50% to about 70%.
[0075] Generator 924A may be gas powered or liquid fuel powered.
However, gas powered is often advantageous at remote wells where
petroleum distillates are difficult to obtain. Where a gas
generator is used, the gas may be purified, partially purified, or
unpurified (e.g., pipeline quality gas or not). Pipeline quality
gas can be provided by conditioning the gas from well source using
techniques known in the art. In a preferred embodiment, the gas
used for generator 924A is only partially purified or
unpurified.
[0076] Advantageously the systems and methods of the invention can
employ a contaminated gas source (i.e., gas that is not pipeline
quality). This can be made possible by delivering the exhaust from
combustion into evaporation system 210A. Contaminates contained in
the exhaust gas may be scrubbed by the moisture in evaporation
system 210A and disposed of with concentrated waste 126 as
described more fully below with respect to the evaporator systems.
In one embodiment, the gas stream used for generator 924A can even
include contaminants such as hydrogen sulfide where the contaminant
has a concentration that prevents the use of the gas in residential
gas pipelines and/or prevents its use in a combustion engine where
the exhaust from combustion would fail environmental regulations.
Gas that is contaminated with contaminates such as hydrogen sulfide
and/or other impurities is often very inexpensive compared to
pipeline quality gas due to the cost of gas conditioning to achieve
the desired purity. In one embodiment, the gas employed in the
generator 924A is not pipeline quality gas. For example, in one
embodiment, the gas employed in generator 924A may not fulfill the
requirements of 40 CFR .sctn.72.2 of the 1999 revisions to 40 CFR
Parts 72 and 75. In one embodiment, the gas employed in generator
924A may include less than 70% methane by volume and/or include
hydrogen sulfide content greater than 0.3 grams/100 scf or greater
than 1.0 grams/100 scf.
[0077] Wastewater treatment system 100A may advantageously be
constructed and or operated at a remote location. Because well
source 212 is typically a natural oil or gas reserve, the location
of well source 212 is dictated by geography rather than
convenience. In many cases, well source 212 may be a substantial
distance from a gas pipeline or a gas conditioning facility. The
use of waste heat from the combustion of gas at a remote location
can provide a synergistic benefit to reducing the cost of disposing
of wastewater produced from a well source. The synergy from power
generation and wastewater treatment near the well source arises
from the shipping costs associated with transporting the wastewater
and the transportation costs associated with transporting a gas in
a pipeline to an alternative location. By producing the power near
the well head, the costs of cleaning and/or transporting the gas
can be avoided with impunity and/or the waste heat from the
generation can be economically put to use in treating the
wastewater from the well source. In addition, since the wastewater
evaporation system 210 is configured to concentrate impurities, the
exhaust from generator 924 (or thermal oxidizer 114) can be easily
"scrubbed" as it is used to heat the wastewater. Even where the
exhaust has relatively high concentrations of impurities, the
exhaust is "scrubbed" of its impurities as it travels through
evaporating system 210. Thus the combination of power generation
and wastewater treatment synergistically benefits each other with
little or no additional expense. While using impure gas to operate
generator 924A may be advantageous in some embodiments, the use of
impure gas is not required. In some cases using higher quality gas
(e.g., pipeline quality gas) may be advantageous (e.g., to reduce
wear and tear on generator 924A).
[0078] The use of generator 924A may be particularly advantageous
for wells that are sufficiently far from a gas pipeline that gas
transportation costs are an issue. In this embodiment, power can be
placed on a grid without having to set up a long distance delivery
system for gas. In this embodiment, the use of pipeline quality gas
may be economical since the power generation also produces a waste
heat that can be used in evaporation system 210A.
[0079] FIGS. 10-12 illustrate water evaporation system 210A which
is an alternative to and can be used in place of water evaporation
system 210. Like elements between system 210 and 210A are
identified by like reference characters. Water evaporation system
210A comprises a housing assembly 211 that includes an evaporator
housing 220 and exit stacks 1016 and 1018. In alternative
embodiments, housing assembly can include additional compartments
or chambers for storing and/or evaporating wastewater.
[0080] Evaporator housing 220 has a substantially flat roof 222 and
an opposing floor 224 that each extend between a first end and an
opposing second end. An encircling sidewall includes a first
sidewall 228 and an opposing second sidewall 330 that each extend
between first end 1032 and an opposing second end 1034. Housing 220
bounds an evaporation chamber 588. First end 1032 may be open to
ambient air or a source of forced air and may include doors 348 and
349. An opening 1004 can provide a doorway that allows entry into
mechanical room 1038 near end 1032.
[0081] Housing assembly 211 further includes a plurality of tubular
exit stacks 1016 and 1018. Exit stacks 1016 and 1018 have an
internal passageway 1005 and 1007, respectively, that is in fluid
communication with the evaporation chamber 588 (FIG. 11) of housing
220. Exit stacks 1016 and 1018 can have any shape or size suitable
for handling the desired volume of air flowing through evaporation
system 210A. Exit stacks 1016 and 1018 can also be combined into a
single stack or split into three or more stacks. In one embodiment,
exit stacks 1016 and 1018 are modular such that they can be
attached and detached from roof 222 of housing 220. Modular stacks
can be advantages when a transportable system 210A is desired,
although modularity is not required. Exit stacks 1016 and 1018 may
include a demisting system described in more detail below with
respect to FIG. 12.
[0082] Turning now to FIG. 11, in the embodiment depicted, an
evaporation chamber 588 is separated from a mechanical room 1038 by
partition wall 556. The bottom portion of evaporation chamber 588
serves as fluid reservoir 572 for receiving wastewater from
pretreatment system 116 and/or raw wastewater stream 106. Fluid
reservoir 572 provides a location for pumping water and for
temporary storage for salts and minerals as water is evaporated
from fluid reservoir 572. Typically water is evaporated until the
salts and/or minerals in fluid reservoir 572 become a concentrated
waste stream such as, but not limited to, a slurry. The
concentrated waste or a portion thereof may then be removed in
batch or as a continuous process. Additional wastewater is added to
the reservoir by directly pumping into the reservoir or through
misting system 1060, described below.
[0083] Partition wall 556 includes a lower divider 1051 that is
water tight to prevent fluid in fluid reservoir 572 from flowing
into mechanical room 1038. An upper portion of partition wall 565
bounds one embodiment of furnace 514A having slits 1048 that allow
air to pass through and enter evaporation chamber 588. The slits
1048 provide an inlet for outside air to enter evaporation chamber
588 above fluid reservoir 572 and create an air flow path 574. Air
flow path 574 extends horizontally within evaporation chamber 588
between slits 1048 and openings 1050, which lead to exit stacks
1016 and 1018. A curved air guide panel 1052 may be provided inside
evaporation chamber 588 below opening 1050 to direct the airflow up
into exit stacks 1016 and 1018. Panel 1052 is not essential, but
can improve the efficiency of the system. A second air flow guide
panel 1042 can be provided in mechanical room 1038 to direct air
into slits 1048 to improve the efficiency of airflow into furnace
514A.
[0084] Air flow path 574 may be produced in whole or in part by one
or more blowers configured to force air into and/or pull air out of
evaporation chamber 588. The blower can be any device configured to
create air flow. In one embodiment, the blower used to produce air
flow in path 574 may be a fan, an electrical generator, a thermal
oxidizer, a gas powered furnace, as discussed above, and/or the
like. The embodiment shown in FIG. 11, includes a fan 1056. Fan
1056 can draw in outside air and/or exhaust from one or more
combustion devices and/or thermal oxidation processes and force the
air into evaporation chamber 588 by passing through furnace 514A.
In alternative embodiments, fan 1056 may be placed inside
evaporator room 1038 and/or within exit chambers 1016 and/or
1018.
[0085] As described above with respect to FIG. 9, water evaporation
system 210A can be coupled to one or more heat sources, such as,
but not limited to, a thermal oxidizer 114, the generator 924, or a
gas furnace 514. The heat source can serve as a blower (e.g., a
forced exhaust stream) or provide a flame or other non-forced form
of heat. In either case, the source of heat is blown into
evaporator evaporation chamber 588. The exhaust or heat can be
ported through end 1032, room 1038, or evaporation chamber 588. In
one embodiment, exhaust from a thermal oxidizer is drawn into the
evaporator through fan 1056 and furnace 514A provides additional
heat through the combustion of natural gas and the exhaust from an
electric generator is piped into evaporation chamber 588 downstream
from partition wall 565. Exhaust from the generator is typically
introduced downstream from a gas powered furnace since exhaust from
the generator can be substantially depleted of oxygen and could
therefore reduce the efficiency of the furnace. Efficient
distribution of airflow through furnace 514A may also be achieved
by utilizing a plurality of dividers (e.g., divider 1058) that
partition air blown by fan 1056. While furnace 514A is shown
positioned within partition wall 565, furnace 514A and/or
additional or alternative heaters may be positioned upstream from
partition wall 565 and/or fan 1056 or downstream of partition wall
565.
[0086] The source of the forced air and the type of forced air may
be selected to provide a desired level of efficiency and to recoup
waste heat produced from ancillary systems to the evaporation
system 210A. As shown and discussed above with respect to FIG. 9,
wastewater treatment system 100A may include one or more of several
different sources heat, including but not limited to, a gas powered
furnace 514, a thermal oxidizer 114 and/or the generator 924. Each
of these three sources of heat and any other heat source may be
used alone or in combination to produce a desired amount of heat
and/or forced air for evaporating water within evaporation chamber
588. In one embodiment, the temperature of air flowing into
evaporator evaporation chamber 588 is in a range from about
15.degree. C. to about 100.degree. C., more preferably about
35.degree. C. to about 50.degree. C. The volume of airflow may be
in a range from about 10,000 cubic feet per minute (cfm) to about
500,000 cfm, more typically about 40,000 cfm to about 100,000 cfm,
or about 50,000 cfm to about 70,000 cfm.
[0087] To increase the evaporation of water from fluid reservoir
572, evaporator 210 can include a misting system 1060. Misting
system 1060 may include a plurality of spray nozzles (e.g., nozzles
596) piping 588, and pump 501 as previously discussed with regard
to water evaporation system 210. Misting system 1060 produces a
fine mist of wastewater that increases the rate of evaporation of
wastewater into air flow path 574 as described above with respect
to the discussion of nozzles 596. Misting system 1060 can include
any number and/or sizes of conduit and/or nozzles configured to
spray wastewater into the air above fluid reservoir 572. Additional
details regarding spray nozzles can be found in co-pending patent
application Ser. No. 12/029,377, filed Feb. 11, 2008, which is
hereby incorporated herein by reference.
[0088] In a preferred embodiment, wastewater introduced into fluid
reservoir 572 is treated to inhibit scaling. In a preferred
embodiment, the descaling treatment is carried out without
softening the water. The descaling treatment can include lowering
the pH, applying crystal forming inhibitors, and/or scaling
inhibitors. In one embodiment, fluid reservoir 572 has a pH less
than about 7, more specifically in a range from about 4.5 to about
6.5, and even more specifically in a range from about 5 to about 6.
Adjusting the pH of the wastewater to a pH lower than about 7
inhibits precipitation of salts and other minerals on the sidewalls
and other surfaces within evaporation chamber 588. The pH of the
wastewater stream can be adjusted by adding a strong acid such as
hydrochloric acid, sulfuric acid, and/or phosphoric acid. The acid
can be added into the wastewater within the evaporator or prior to
the evaporator. As described more fully below with regard to FIG.
13, acid is preferably added in pretreatment system 116. However,
the use of acid in pretreatment system 116 is not required. Crystal
forming inhibitors and/or scaling inhibitors can be added in or
upstream from reservoir 572. Unlike existing wastewater treatment
systems that use high pressure, evaporation system 210 has been
found to work well without using expensive, traditional water
softening techniques (e.g., removing calcium and magnesium using a
counter ion such as sodium carbonate or ion exchange). Evaporation
system 210 can be operated efficiently without removing the scaling
minerals by adjusting the pH and/or adding scaling and/or crystal
forming inhibitors. It is believed that system 210 can be operated
efficiently without water softening due to its ability to operate
at low or even ambient pressures.
[0089] FIG. 12 describes exit stack 1018 in greater detail. Exit
stack 1018 is formed from sidewalls 1288, 1290, 1292, 1294 that
encircle passageway 1007. During use, an airstream 1260 within
passageway 1007 delivers air received from evaporation chamber 588
(i.e., air from air flow path 574) toward outlet 1002 where the
moisture laden air may be received in the open environment. Air
travelling through passageway 1260 is forced through a demister
1296, which includes one or more water coalescing pads (e.g., pads
1262 and 1268). The demister 1296 can include any number of water
coalescing pads appropriate for removing suspended moisture of a
desired size from air stream 1260. The water coalescing pads of the
demister are configured to provide a large surface area in which
the air stream 1260 passes to reach outlet 1002 of housing assembly
211. In one embodiment, the average surface area of the one or more
pads may be in a range from about 100 m.sup.2/m.sup.3 to about 500
m.sup.2/m.sup.3, more typically in a range from about 50
m.sup.2/m.sup.3 to about 250 m.sup.2/m.sup.3. The thickness of the
one or more water coalescing pads depends on the configuration of
the surface area, the number of different sized water coalescing
pads, and the desired water removal to be achieved. However, the
thickness will typically be in a range from about 50 mm to about
1500 mm, more specifically about 150 mm to about 500 mm.
[0090] The demister typically includes a pattern of walls and
channels that allow air to flow therethrough but that cause
suspended water droplets to collide and coalesce to form larger
water droplets that are heavy enough to fall downward through
airstream 1260, which is flowing upward. In alternative embodiments
airstream 1260 can flow horizontally or at other angles so long as
the collected water can be separated from the evaporated water in
airstream 1260.
[0091] The size and configuration of the surfaces in the demister
and the thickness of the demister (i.e., the length of the flow
path through the demister) determines the size and percentage of
the water droplets that will coalesce. In general, a longer flow
path (i.e., thicker demister) results in a high percentage of a
given size water droplet being coalesced and narrower channels
and/or thinner wire surfaces results in smaller droplets being
coalesced.
[0092] FIG. 12 illustrates demister 1296 having a first water
coalescing pad 1262 and a second water coalescing pad 1268. Pad
1262 is configured to remove relatively large water droplets from
airstream 1260 and second coalescing pad 1268 is configured to
remove relatively finer water droplets from stream airstream
1260.
[0093] First coalescing pad 1262 includes a plurality of wall
structures that define channels through which air stream 1260 is
forced to flow over. Wall structures 1266 can have any shape
suitable for directing airflow. For example, as shown in FIG. 12,
wall structures 1266 can be arranged to form vanes that are stacked
in layers and in fluid communication to cause airflow to travel
horizontally and vertically through pad 1262. In one embodiment,
wall structures 1266 can be placed at angles to create a chevron
cross-section. In yet another embodiment, water coalescing pad 1262
can be a layer of regular or irregular shaped structures such as
packing materials. Examples of packing material include structured
grid packing and random packing materials.
[0094] The structure of first coalescing pad 1262, which includes
wall structures 1266, is configured to remove water droplets of a
particular size. For example, the dimensions and spacing of the
wall structures 1266 can be configured to remove water droplets
with a diameter of about 20 microns to 100 microns or larger. Water
coalescing pads having wall structures are typically useful for
removing relatively larger water droplets as compared to a wire
mesh pad (e.g., water coalescing pad 1268, described below). In one
embodiment, the water coalescing pad 1262 has wall structures 1266
with a thickness in a range from about 0.5 mm to about 5 mm and
spacing in a range from about 2 mm to about 50 mm, more
specifically about 9.5 mm (3/8 inch) to about 12.7 mm (1/2 inch).
In one embodiment, the wall structures 1266 are configured to
coalesce water droplets with a diameter in a range from about 20
microns to about 100 microns. The coalescing pad 1262 can include
any number of layers of wall structures 1266. The thickness 1263 of
coalescing pad 1262 is typically between about 100 mm and 1000 mm,
more typically between about 200 mm and 500 mm.
[0095] Second water coalescing pad 1268 shown in FIG. 12 is formed
from a wire mesh. The wire mesh is generally formed from a metal,
but can be made from other materials suitable for making meshes
with the desired surface area. The thin wires of the mesh of
coalescing pad 1268 provide a desired surface area for water
droplets to collect and collide with one another. In general,
thinner gauge wire is more effective at removing smaller sized
water droplets and thicker wire is more effective at removing
relatively larger water droplets. In one embodiment the average
thickness of the wire can be in a range from about 0.05 mm to about
1 mm, more typically in a range from about 0.2 mm to about 0.5 mm.
In one embodiment, the size and configuration of the wire mesh in
coalescing pad 1268 may be configured to remove water droplets from
airstream 1260 that have a diameter in a range from about 0.5
microns to about 50 microns, more typically about 1 micron to about
20 microns.
[0096] The wire mesh of coalescing pad 1268 is typically woven
together, although other methods of interconnecting and/or linking
the wires may be used. In one embodiment, coalescing pad 1268
includes a plurality of layers of wire mesh. For example,
coalescing pad 1268 can include 50-200 layers of woven wire.
Moreover, coalescing pad can have layers with different sized wires
and/or spacing. For example, in one embodiment, an upstream portion
of the coalescing pad 1268 can have a first coarser wire and/or
lower surface area and a downstream portion can have a finer wire
diameter and/or higher surface area. The thickness 1269 of
coalescing pad may be in a range from about 100 mm to about 1000
mm, more typically between about 150 mm and 500 mm.
[0097] Examples of suitable coalescing pad that can be used in
demisters according to some embodiments of the invention are sold
by Amistco Separation Products, Inc. located in Alvin Tex.,
USA.
[0098] The exit stacks 1016 and 1018 preferably include a wetting
system 1270 configured to keep a downstream surface 1267 of
demister 1296 wet. Any hardware suitable for applying a liquid such
as clean water or wastewater to the downstream surface 1267 may be
used. In one embodiment, wetting system 1270 include a plurality of
conduits (e.g., conduit 1273) that traverse exit stack 1018 near
outlet 1002 above demister 1296. The plurality of conduits 1294
each include a plurality of sprayers 1272, such as sprinklers,
misters, nozzles, drip lines or other suitable type of water
distribution apparatus. The sprayers 1272 are configured to spray
the surface area with sufficient water to maintain a wet surface.
Wetting system 1270 can be coupled to a water supply using valves,
pumps, conduits and other techniques known in the art. In one
embodiment, the wetting system 1270 uses wastewater as the water
source.
[0099] In operation, the sprayers 1272 can be operated continuously
and/or at timed intervals and/or at desired flow rates to maintain
a desired wetness. In one embodiment, wetting system 1270 is
operated periodically to provide periodic water flow into exit
stack 1018, while minimizing the extent to which the water flow
impedes airstream 1260 through demister 1296. In one embodiment,
the interval for wetting surface 1267 is at least about every hour,
more specifically at least about every half hour, and even more
specifically at least about every fifteen minutes.
[0100] Surprisingly, maintaining a wet surface on the demisters
can, in many circumstances, substantially impede the escape of
salts and dissolved minerals from the evaporator evaporation system
210A without undo restriction on airstream 1260. Using a wetting
system 1270 allows the airstream 1260 to carry a higher
concentration of water without losing salts at the interface
between the demister and the ambient air. Wetting the surface
dissolves salt and/or minerals that would otherwise collect on the
surface of the demister and gravity can draw the water back into
the airstream 1260, where concentrated salts will fall back down
into fluid reservoir 572. The use of wastewater to wet the surface
of the demisters may also be advantageous because a portion of the
water will be evaporated into the ambient air, which further
increases the evaporation efficiency of the system.
[0101] Demister 1296 can have any shape suitable for placement in
exit stack 1018 so long as airflow can be directed through demister
1296. To facilitate flow of the air stream 1260 through demister
1296, the demister can include brackets and expansion hardware that
allows the pads 1262 and 1268 to expand and contract without
forming gaps between the walls of exit stack 1018 and demister
1296. FIG. 12 shows plate 1264 with casing hardware 1278 and
expansion hardware 1276. Expansion hardware 1276 allows plate 1264
to expand or contract while still directing airflow through the
plates of demister 1296.
[0102] The demister 1296 is useful for preventing dissolved salts
and minerals from escaping the evaporator system. Water that has
been suspended in airstream 1260, but not evaporated, typically
contains salts and/or minerals. Water that is actually evaporated
(i.e. gaseous) contains very little if any dissolved salts. By
retaining water vapor within the evaporator system, the salts and
minerals can be more efficiently concentrated and properly disposed
of.
[0103] The proper air flow and temperature within exit stack 1018
can be maintained using one or more sensors. Evaporation system
210A may include temperature sensors, humidity sensors, pressure
sensors, mass air flow sensors and the like either inside or
outside the airflow stream (i.e., inside or outside the system).
FIG. 12 illustrates pressure sensors 1280 and 1282, which can be
used to determine a pressure drop across demister 1296. Humidity
sensor 1284 and temperature sensor 1286 may be used alone or in
combination with pressure sensors 1280 and 1282 to determine proper
flow and water capacity of airstream 1260. The air flow and
temperature within exit stack 1018 can be controlled using control
unit 136, which can use the readout from sensors 1080, 1082, 1084,
1086 and/or sensors 922, to change the state of system 210A.
[0104] The present invention also includes methods for evaporating
a fluid. In one embodiment, the methods can include all or a
portion of the following steps: (i) pooling a fluid within a
reservoir that is bounded by an elongated housing, the housing also
bounding an air flow path that is disposed over top of and that
communicates with the reservoir, the air flow path extending from
an air inlet opening in the housing to an air outlet opening in the
housing; (ii) creating a flowing air stream wherein air in the
environment outside of the housing flows into the air flow path
through the air inlet opening, travels along the air flow path so
that the air passes over the fluid within the reservoir, and then
exits out of the housing through the air outlet opening; (iii)
spraying the fluid within the reservoir into the air flow path
within the housing and above the reservoir; and (iv) coalescing
suspended water droplets in the air stream on a demister upstream
from the air outlet opening and downstream from the reservoir, the
demister including at least one water coalescing pad configured to
coalesce suspended water droplets in the air stream. In one
embodiment, the method the step of coalescing suspended water
droplets includes removing at least about 50% by weight of water
droplets in the air flow stream having a size between about 1
micron and about 20 microns in diameter. More specifically, at
least about 80%, 90%, or even at least about 99% of water droplets
having a size between about 1 micron and about 20 microns in
diameter are removed. Alternatively, or in addition, the method may
include the step of coalescing at least about 50% by weight of
water droplets in the air flow stream having a size between about
20 micron and about 100 microns. More specifically, at least about
80%, 90%, or even at least about 99% of water droplets having a
diameter of about 20 microns to about 100 microns are removed.
[0105] The method can also include wetting a downstream surface of
the demister. The wetting may be carried out continuously or
intermittently. For example, the surface can be wetted at intervals
of less than about 1 hour, more specifically at intervals of less
than about 0.5 hour, and even more specifically at intervals of
less than about 0.25 hour. The method may also include generating
electrical power using an electrical generator to produce an
exhaust stream; supplying the electrical power to a power grid
and/or powering a control unit configured to operate the electrical
generator; and using the exhaust stream to create at least a
portion of the flowing air stream. In one embodiment, the method
can also include regulating the speed of the flowing air stream
based on the temperature or humidity within or outside of the
housing. This step can be carried out using a control unit and one
or more sensors inside and/or outside the housing. This step can be
carried out using a control unit and one or more sensors inside
and/or outside the housing. The method can also be carried out
using any of the features described above with regard to FIGS. 1-12
or with regard to the pretreatment system described more fully
below.
[0106] As mentioned above, the present invention includes systems
and methods wherein the well source is a brackish water such as sea
water. In this embodiment, the desired product from the systems and
methods may be a desalinated water condensed from the airflow
stream downstream from the demisters. The evaporated water in
airstream 1260 can be condensed downstream from demister 1296 and
recovered to produce a desalinated water. The desalinated water may
be potable water or an irrigation water. Where potable water is
desired, the heat source for evaporation system 210A typically
includes a furnace and the exhaust heat from the combustion of
highly polluting materials is typically avoided.
[0107] The hot moist air exiting evaporator evaporation system 210A
at opening 1002 can be directed to any condenser known in the art
for condensing evaporated moisture from a humid air supply. For
example, moisture can be cooled using a heat exchanger that cools
the purified evaporated stream exiting evaporator evaporation
system 210A using ambient air and/or a coolant such as water,
including sea water. Those skilled in the art are readily familiar
with condensers that can be used to produce condensed water from a
high moisture content stream such as airstream 1260 downstream from
demister 1296. Moreover, those skilled in the art are familiar with
systems including pumps, valves, storage tanks, etc. that are
useful for handing the desalinated water to obtain it from the
ground or a body of water and/or for injecting concentrated water
back into the environment. Additional details regarding condensers
and systems for drawing brackish water from the natural environment
can be found in US Patent Publication No. 2007/0084778 to St.
Germain and US Patent Publication No. 2002/0178723 to Bronicki,
which are both hereby incorporated herein by reference.
[0108] FIGS. 13-16 illustrate one example of a pretreatment system
116 that can be used in wastewater treatment system 100A shown in
FIG. 9. Pretreatment system 116 includes one or more upflow induced
air separators such as separators 1304 and 1306. Pretreatment
system 116 is configured to separate solids, water, dissolved
hydrocarbons, and gaseous compounds into separate streams.
Pretreatment system 116 includes a wastewater stream 106 produced
from an oil and gas source and therefore includes components
typically found in the wastewater produced from a well source as
described above.
[0109] The wastewater stream 106 is treated with polymer 1308 and
optionally acid 1310 to form conditioned wastewater stream 1312,
which is then delivered to gas induction apparatus 1314. Gas
induction apparatus 1314 mixes a gas into stream 1312 to form
induction stream 1310. Induction stream 1310 is injected into
upflow separator 1304 via inlet 1322. Upflow separator 1304
separates the wastewater stream into a recycle gas stream 1316,
volatile organic compounds 1318, a foam stream 1324, a pretreated
wastewater stream 1323, and in some cases a solids stream 1336.
[0110] In one embodiment, pretreated wastewater stream 1323 can be
treated in a second upflow separator 1306 to ensure complete
separation. Or, alternatively wastewater stream 1324 can be
delivered to water evaporation system 210A via stream 1330. The
additional pretreatment of stream 1323 can be selectively
controlled by valve 1337. For example, if a certain quantity of
solids and/or hydrocarbons remains in stream 1323, valve 1337 can
be set to deliver stream 1323 to a second gas induction apparatus
1338 and subsequently to second upflow separator 1306. In an
alternative embodiment, pretreatment system can be configured to
always deliver stream 1323 to a second upflow separator 1306 or
even one or more additional upflow separators to achieve a desired
level of separation between the water and hydrocarbons.
[0111] The second gas induction apparatus combines stream 1323 with
a gas from upflow separator 1306 via line 1344 and/or from ambient
air to form a second induction stream 1342, which is then
introduced into the second separator 1306 via inlet 1340. A second
quantity of polymer 1338 can also be added to stream 1323 to
enhance separation of the water and polymer. Second upflow
separator 1306 creates a stream 1319 of volatile organic compounds,
a foam stream 1326 that includes separated hydrocarbons, a
pretreated wastewater stream 1332 and in some cases a second solid
waste stream 1334.
[0112] The polymer 1308 is added to the wastewater stream 1312 and
optionally added to stream 1323 in sufficient quantities to enhance
separation of the hydrocarbons and the water fraction of the
wastewater. Any polymer can be used that will enhance the
interaction of hydrocarbons with the surface of the water. The
polymer can be a high or low molecular weight, anionic, or cationic
polymer that is water or emulsion soluble. Examples of suitable
polymers include polymamines and polyamides (e.g., polyacrylamide).
Other flocculents known in the art can be used alone or in
combination with the polymer 1308 to facilitate separation of the
hydrocarbons and the water. The polymer can be continuously metered
into the wastewater stream 106 or alternatively a desired quantity
can be added in batch to a certain quantity of wastewater to obtain
a desired concentration. In one embodiment, the concentration of
the polymer in the wastewater is in a range from about 1 parts per
million (vol. %) to about 300 parts per thousand (vol. %) more
specifically about 2 ppm (vol. %) to about 50 ppm (vol. %), and
most preferably about 3 ppm to about 10 ppm. The use of a polymer
can have a substantial impact on the separation of hydrocarbons
from water. In one embodiment, wastewater departing pretreatment
system 116 has a hydrocarbon content less than about 150 ppm, less
than about 50 ppm, or even less than about 10 ppm.
[0113] An acid may also be metered or batch added to the wastewater
stream 1312 to lower the pH. Examples of suitable acids include
concentrated hydrochloric acid and concentrated sulfuric acid.
Hydrochloric acid may be preferred in some embodiments. The use of
an acid to lower the pH of the wastewater stream in combination
with the use of a polymer was surprisingly found to increase the
separation of hydrocarbons from wastewater in the upflow separator
1304 as compared to polymer alone. However, lowering the pH is not
essential for separation in the upflow separator. Moreover,
substantial benefits throughout system 100 were observed from
adding acid to wastewater stream 106. The use of an acid has been
found to substantially reduce buildup of salt and other minerals on
the components of system 100, and particularly the components of
evaporation system 210 that come into contact with wastewater
(including misted wastewater as described above). Thus, while
adding acid prior to upflow separator 1304 can be desirable, the
addition of acid may also be beneficial in evaporation system 210
or in line between pretreatment system 116 and evaporation system
210. In one embodiment, the acid is added in sufficient quantities
to lower the pH to within a range from about 4-7, more specifically
about 4.5-6.5, and even more specifically about 5-6. The pH of the
wastewater stream can be measured using techniques known in the art
(e.g., a pH meter).
[0114] FIG. 14 illustrates the upflow separator 1304 in additional
detail. Upflow separator includes a vessel 1403 with a riser 1458
disposed therein and a weir wall 1460 positioned above riser 1458.
As mentioned, induction stream 1310 is injected into separator 1304
via inlet 1322. The mixture of gasses, polymer, water,
hydrocarbons, and solids are forced up through tubing 1454 of riser
1458 and ejected through a plurality of riser outlets 1456, which
are sized and configured to cause foaming. Riser outlets 1446 are
also referred to herein as injection openings. In one embodiment,
riser outlets 1456 have a surface area that collectively are about
the same surface area as a horizontal cross-section of riser 1458.
By keeping the surface area of the riser outlet openings about as
large as the cross-section of riser 1458, the injection of
induction stream 1310 will have minimal turbulence, which benefits
separation. In one embodiment, the collective surface area of riser
outlets 1456 is at least about 0.5 to 2.0 times the surface area of
a horizontal cross section of riser 1458. While riser outlets 1456
have been illustrated in this embodiment as being circular, riser
outlets can have any shape and/or be combined into a single
opening.
[0115] The mixture ejected from riser 1458 forms a foam-water
mixture that separates based on density into a water fraction 1470,
a foam fraction 1468 and a gaseous fraction 1466. Foam fraction
1468 floats above the water fraction 1470 because it is lighter
than water. The water fraction 1470 collects near the bottom of
vessel 1403. The water level (i.e., the interface between fraction
1470 and 1468) can be maintained by controlling the flow of water
out of outlet 1453. If the rate of flow out of outlet 1453 is
greater than the accumulation of separated water entering through
riser 1458 then the water level rises. Conversely, if the rate of
flow out of 1453 is greater than the rate of water accumulation
from outlet 1453, the water level drops. The foam fraction 1468 is
allowed to accumulate in vessel 1403. The accumulating foam rises
above water fraction 1470 until the foam flows over weir wall 1460.
Foam flowing over weir wall 1460 flows along a slanted support 1462
and exits vessel 1403 as stream 1324. The top of weir wall 1460 and
opening in vessel wall create the opening through which foam flows
out of vessel 1403.
[0116] Gas fraction 1466 is lighter than foam fraction 1468 and
collects in vapor space above weir wall 1460 and exists vessel 1403
as stream 1316 (i.e., gas induction line) or as stream 1318 (i.e.,
VOCs).
[0117] Outlet 1136 can be selectively opened to flush solids that
may collect in the bottom of vessel 1403, depending on the presence
or absence of solids in wastewater stream 106. One or more sprayers
(e.g., sprayers 1450 and 1452) can be provided to facilitate
flushing vessel 1403.
[0118] The use of polymer and optionally acid enhances the degree
and/or rate to which hydrocarbons are separated in vessel 1403.
Because foam fraction 1468 has a high surface area, the polymer in
the foam is able to better attract hydrocarbons than polymer in the
water fraction 1470. This feature can result in rapid separation of
the hydrocarbons from the water fraction. This feature results in
much higher throughput of material for a given volume of vessel
1403, thereby reducing capital costs and reducing the number of
successive upflow separators needed to sufficiently treat the
wastewater stream. In some embodiments, sufficient separation can
be achieved with a single separation vessel or just two separation
vessels, although more than one or two upflow separators can be
used depending on the circumstances of the wastewater stream.
[0119] In one embodiment, upflow separator 1304 may be efficiently
operated by periodically purging foam fraction 1468. Periodically
purging foam fraction 1468 prevents vessel 1403 from becoming
clogged and improves the separation of gases, solids, water, and
foam. To purge foam fraction 1468, water flow through outlet 1453
can be halted or reduced to allow the water level to rise. FIG. 15
illustrates a purge procedure in which the water level has flowed
over weir wall 1460 and out vessel 1403 through line 1324. Foam
fraction can be substantially purged by opening an alternative
opening (not shown) other than line 1324 and/or by limiting the
amount of water that is allowed to flow out line 1324. In one
embodiment, purging foam fraction 1468 can be carried out on a
regular period basis as a preventative measure. In one embodiment,
foam purging is carried out at least daily during operation, more
specifically at least hourly, even more specifically at least about
every 30 minutes, and even more preferably at least about every 15
minutes during operation.
[0120] In some cases, solids such as small rocks, dirt, and/or sand
can accompany the wastewater stream and may collect in the bottom
of reactor 1403. FIG. 16 illustrates an upflow separator that has
been operated for a sufficient period of time for a solid fraction
1472 to collect on the bottom of vessel 1403. Solids fraction 1472
may be purged by opening a valve to allow solid fraction 1472 to
flow through outlet 1336. To facilitate cleaning of vessel 1403, a
plurality of sprayers (e.g., sprayers 1450 and 1452) may be
operated during the purging of solids fraction 1472. Solids
fraction 1472 can be purged for any amount of time sufficient to
remove the desired portion. In some embodiments, water level in the
vessel 1403 can drop during the solids purging step. The frequency
with which solids purging is carried out will depend on the source
of the wastewater stream. However, in one embodiment purging the
solids fraction can be carried out at least about monthly, more
specifically at least about weekly, and even more specifically at
least about daily.
[0121] Additional details regarding upflow separator systems that
can be used in the present invention include, but are not limited
to the features of the upflow separators described in U.S. Pat. No.
4,564,457, which is hereby incorporated herein by reference.
[0122] In one embodiment, the invention includes methods for
separating oil and gas contaminants from water. In one embodiment,
the methods include all or a portion of the following steps: (i)
providing an upflow separator apparatus include a vessel defining
an internal space having a top end and a bottom end. A riser is
positioned within the vessel and is coupled to an inlet thereof and
extending upward from the bottom end of the vessel, the riser
having one or more injection openings configured to produce a foam
from an injection stream; (ii) providing an induction apparatus in
fluid communication with the inlet of the vessel and with a
wastewater stream; (iii) mixing a polymer with the wastewater
stream; (iv) adjusting the pH of the wastewater to less than about
7; (v) inducing gas into the wastewater stream to produce an
injection stream; (vi) emitting the injection stream from the
injection openings to produce a foam; (vii) allowing the emitted
injection stream to separate into a water fraction, a foam
fraction, and a gas fraction; (viii) recovering the separated water
fraction, foam fraction, and gas fraction; and (ix) introducing the
recovered water fraction into a fluid reservoir of a water
evaporator, the water evaporator including a housing bounding the
fluid reservoir formed at or adjacent to a floor, the housing also
bounding an air flow path that is disposed over top of and that
communicates with the fluid reservoir; an inlet opening formed at a
first location of the housing, the inlet opening being configured
to introduce air from outside of the housing into the air flow
path; an outlet opening formed at a second location of the housing
and communicating with the air flow path, the outlet opening
communicating with the open environment outside of the housing; a
blower for forcing air into the air flow path and out the outlet
opening; and a misting system configured to spray fluid pooled
within the reservoir into the air flow path above the fluid
reservoir.
[0123] The method can employ any of the features described above
with respect to the pretreatment system described in FIGS. 13-16
and/or evaporator systems described with respect to FIGS. 1-12.
[0124] In view of the foregoing, it is appreciated that different
embodiments of the present invention can be used to achieve a
number benefits. For example, the water evaporation system can be
designed to be transportable. As such, the water evaporation system
can be shipped directly to a well head, storage tank, pond, or
other site where it is desired to evaporate a fluid such as water.
The water evaporation system thus eliminates the need to ship the
fluid and eliminates the need to pay for disposal fees at a
disposal facility. Once use of the system at one location is
completed, the system can then be moved to another location.
Likewise, if additional capacity is needed, two or more water
evaporation systems can be positioned at a single site. In
alternative embodiments, it is appreciated that the water
evaporation system need not be transportable but can be built as a
fixed structure at a desired location.
[0125] Additional benefits of the water evaporation system are that
some embodiments can be designed to be self-contained for use in
remote locations. Furthermore, because housing 220 is enclosed, the
system can be used in high winds and in any other environmental
conditions. In some embodiments, depending on whether conditions,
it is appreciated that the water evaporation system can be used to
evaporate more than 200 barrels of water per day and more commonly
more than 300 or 400 barrels of water per day. Although the present
invention is primarily discussed with the evaporation of water, it
is also understood that the inventive water evaporation system can
also be used for the evaporation of other types of fluids.
[0126] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. For example, it is appreciated that the different
features of wastewater treatments systems 100 and 100A and the
alternatives thereof can be mixed and matched to form other system
configurations. Thus, the described embodiments are to be
considered in all respects only as illustrative and not
restrictive. The scope of the invention is, therefore, indicated by
the appended claims rather than by the foregoing description. All
changes which come within the meaning and range of equivalency of
the claims are to be embraced within their scope.
* * * * *